San Francisco has never been a very good town for bicyclists. In addition to the usual dangers common to urban areas--heavy traffic, double-parked cars, motorists using cell phones--local cyclists have to contend with such uniquely San Francisco problems as how to get up Potrero Hill without having a heart attack.

Unless Schwinns grow wings someday, that last problem may never be completely solved. Even so, by some counts as many as 11,000 San Franciscans bicycle to work every day, and the Department of Parking and Traffic's Bicycle Program is trying to make life a little easier for them. Completely funded by the Bay Area Air Quality Management District and other non­city-government sources, the Bicycle Program has already set up a bicycle information hotline (585-BIKE) and replaced tire-eating sewer grates on Market Street.

One of its most ambitious projects is the new Bicycle Route Network, 180 miles of routes from residential areas to major destinations. Like highways, each route is numbered, odd numbers for north-south and even numbers for east-west. You can find a complete network map on page A14 of PacTel's Yellow Pages. Once on your bike, follow the street signs showing a green oval with a bicycle, the route number and the top of the Golden Gate Bridge poking through fog. When the project is completed, there will be 3,000 of these signs. According to Adam Gubser, bicycle program assistant manager, the network is modeled loosely on Muni's system, with routes chosen on the most bike-safe streets available.

When possible, the routes also take the least hilly means, but sometimes there's no way around heart-attack alley. "Clipper Street," Gubser says, "is painful."

Fortunately, the new Bikes on Muni program features bike racks on the front of buses that ply particularly hilly routes. So if you do need to climb up Clipper Street, simply take your bike on the 37 Corbett. You can always tell your friends you pedaled all the way.